(1) Field of the Invention
The present invention relates to the field of controlling aircraft by means of at least one actuator. By way of example, such actuators may comprise hydraulic jacks, servo-controls, or electric motors that serve to control the attitude and the path of the aircraft relative to three main axes, namely a yaw axis enabling the aircraft to pivot, a pitching axis enabling the aircraft to pitch up or down, and a roll axis enabling left/right inclination of the aircraft to be modified, and also the vertical axis for maintaining the height of the flight.
(2) Description of Related Art
By way of example, such actuators can also act on flaps or slats to increase or reduce the lift of a wing of the aircraft, and on air brakes in order to increase or reduce the drag of the aircraft.
In addition, in the particular situation where the aircraft to be controlled is a drone of the multirotor type, such actuators may also be formed directly by electric motors. Such electric motors are motors having a variable speed of rotation and they are then controlled in order to drive rotation of the various rotors constituting a rotary wing that serves in particular to provide the aircraft with lift, and also to determine its attitude, as defined by the pitch and roll attitude angles of the aircraft, thereby enabling the path of such an aircraft to be controlled.
In general manner, while piloting an aircraft, on-board sensors serve to measure flight parameters. Such flight parameters may in particular be attitudes, speeds, or accelerations of the aircraft along the three main axes. These flight parameter measurements are transmitted to calculation means serving to manage control setpoints for the actuator(s), used to control the aircraft in compliance with at least one control law.
Furthermore, in order to control certain aircraft that require control means to have redundancy, and as described in particular in Document EP 2 595 023, it is also known to make use of at least two calculation means or processors serving to generate two mutually distinct control laws in parallel. Thus, if one of the control means or processors fails, a backup control means/processor can take over and generate the control law used for controlling the actuator.
Nevertheless, in order to achieve such redundancy in the control of the actuator, the at least two calculation means or processors need to be mutually synchronized in terms of their calculation clocks, and they also need to exchange proportional, derivative, and/or integral correction data for application to the signal derived from a control setpoint in order to control one or more actuators. Such synchronization of calculation means is very complex to achieve in practice and requires sophisticated synchronization means and calculation means that are unusual in that they are capable of mutually communicating information about real time variations of the flight parameters. Document U.S. Pat. No. 3,764,095 describes such means for synchronizing data between two sophisticated calculation means.
Furthermore, it is clear that the greater the number of calculation means included in a control system for generating control laws in parallel, the more difficult it becomes to synchronize them.
Furthermore, and as described in Document DE 32 25 724, a method is also known of remotely monitoring steering commands for a passenger vehicle such as a bus. In addition, that method describes using two mutually distinct control channels, one acting on the steering in the vehicle while the other is available on standby.
In addition, in order to obtain operational availability of both channels, provision is made only for the active channel and the standby channel to be swapped over periodically, and for this to be done with a short cycle time.